BH dynamical friction

Tracking black hole orbits in cosmological simulations: In (missing reference) we introduced a new calibrated model for N-body dynamical friction acting on supermassive black holes, which is essential to faithfully represent the physics of these objects in cosmological hydrodynamics simulations. Limited spatial and mass resolution and the associated discreteness noise in these calculations make following the dynamics of black holes especially challenging. In our study we proposed a correction for unresolved dynamical friction, calibrated on simulations run with the code KETJU, in which gravitational interactions of black holes are not softened. We demonstrated that our correction is able to sink black holes with masses greater than the dark matter particle mass at the correct rate. Combined with a correction for stochastic heating this approach is now applicable to next generation cosmological hydrodynamics simulations that jointly track galaxy and black hole growth with realistic black hole orbits. We are presently inlining it into the AREPO code for new LtU simulations using this technique.